The Operative Plumbers' Society of New South Wales was in existence by May 1900 and amalgamated with the Australian Plumbers and Gasfitters Employees' Union in 1916.

The Plumbers and Gasfitters Employees' Union was formed in 1911, at a conference held at the Trades Hall in Victoria. Plumbers' unions in Queensland, South Australia and Victoria united to create the foundation branches of the federal union. In 1912 the union was federally registered under the Commonwealth Conciliation and Arbitration Act as the Australian Plumbers and Gasfitters Employees' Union. The new union covered workers in plumbing, gasfitting, pipefitting and domestic engineering work. NSW, Tasmania and Western Australia joined the union in 1916, 1918 and 1973 respectively. In 1928 it changed its name to the Plumbers and Gasfitters Employees' Union of Australia. Initially, the union was a loose federation of state Branches with substantial differences in pay and conditions. From the 1970s onwards however, it was transformed into a union operating on a strong national basis with national awards and common rates of pay and conditions. In March 1993 it amalgamated with the Electrical Trades' Union to become the Electrical, Electronic, Plumbing and Allied Workers Union of Australia (EPU), with separate electrical and plumbing divisions. In 1994 the EPU joined with the Communications Workers' Union of Australia to form the Communications Electrical Electronic Energy Information Postal Plumbing and Allied Services' Union of Australia, known as the Communications, Electrical and Plumbing Union (CEPU).

The New South Wales Plumbers and Gasfitters Employees' Union operated independently to the Plumbers and Gasfitters Employees' Union of Australia in the period 1979 to 1985. The Federal Council intervened by establishing a separate office in Sydney and a court case in 1981 upheld the Federal union's right to organise in New South Wales. The struggle for members and for recognition by the NSW Labor Council continued until the resignation of the State union's Secretary in 1985.